1. Technical Field
The present invention relates to improvement of optical interconnection apparatuses (optical circuit boards) for connecting parts or devices such as optical components, optical circuit packages, optical circuit devices used for optical communication and optical information processing to each other.
2. Related Art
In connecting plural optical components in an optical circuit package to each other, in connecting plural optical circuit packages to each other, and in connecting optical circuit devices installed with optical circuit packages, an optical connector is disposed at an end of an optical component, an optical circuit package, and an optical circuit devices, which are connected to each other by optical fibers. In this case, since the optical fiber should be arranged with a loose thereof, complicated routing causes optical fibers to interfere with each other and they are entangle in the form of a bird""s nest, for example, over the optical circuit package or inside or behind the optical circuit devices. Therefore, large spaces and large amount of labor for routing the optical fibers have been required.
In contrast to the above optical connecting manner for optical fibers, easy methods for solving the above problems by routing optical fibers in a 2-dimensional plane have been proposed. For example, as disclosed in Japanese Patent No. 2574611, an optical interconnection apparatus, in which a routing of optical fibers is secured on a sheet or a substrate on which an adhesive is coated, is proposed. In the production of the optical interconnection apparatus, the optical fibers are routing on a substrate or an optical fiber jacket on which an adhesive is coated so as to form a routing pattern, over which the same material as the substrate is covered so as to form a protecting layer. The routed optical fibers intersecting each other are secured by the protecting layer.
The optical interconnection apparatus having the above structure may be used on an optical circuit package or between optical circuit devices (rack). However, no measures of preventing fire have been provided. In particular, according to recent safety regulations for electrical or electronic apparatuses in recent years, measures of preventing fire, namely, flame resistance, is indispensable. This requirement is essentially the same as for the optical parts. However, in the optical interconnection apparatuses which have been proposed, the structure emphasizes securing and protecting the optical fibers, as described above. Therefore, the adhesive is exposed at the circumferential edge surface of the optical interconnection apparatus, and is feared catching fire from there. Acrylic adhesives (pressure sensitive adhesives) are generally used as the adhesive, and most of these are flammable. Although acrylic adhesives with flame resistance are provided, these adhesives do not have sufficient securing properties for the optical fibers due to addition of a flame retardant agent, so that problems such as dishevelment of the routing pattern of the fibers may readily occur, and are not suitable for practical use.
The present invention has been made to solve the problems in the above conventional art. An object of the invention is to provide optical interconnection apparatuses, in which plural optical fibers are routed, which have flame resistant maintaining performance and operational efficiency.
The invention provides an optical interconnection apparatus comprising an adhesive layer having a 2-dimensional plane and optical fibers secured on the adhesive layer. The optical fibers are routed on the adhesive layer so as to have at least one of an intersection portion, a bent portion, and a changing portion of fiber pitch, and to have a end portion outwardly projecting from the adhesive layer. The projecting end portion is attached optical connection. At least a portion of the circumferential edge surface of the adhesive layer is covered by a flame resistant material at an end of the optical fiber and in the vicinity thereof.
When fire occurs in an optical circuit device, the fire may be transmitted from one part to another part via optical fibers. According to the optical interconnection apparatus of the invention, since at least a portion of the vicinity of the peripheral edges of the adhesive layer is covered by a flame resistant material at an end of the optical fiber and in the vicinity thereof, it can be inhibited to catch fire from the optical fibers to the adhesive layer. Therefore, flame resistance can be obtained maintaining the performance and the operational efficiency thereof.
It should be noted that xe2x80x9cflame resistancexe2x80x9d is defined as described below in detail, such that the evaluation of the flame resistance is 94V-2 or more by a xe2x80x9c20 mm vertical burning testxe2x80x9d specified under the UL94 safety regulation. In particular, when five samples are burned two times under predetermined conditions, the flaming time of each sample at each burning is 30 seconds or less, and the total time of the flaming of five samples in two burning is 250 seconds or less.
In the invention, the adhesive layer is preferably covered by a flexible protecting resin layer for protecting and securing the optical fibers. A edge-dam with flame resistance is preferably provided at a circumference of the adhesive layer, the protecting resin layer is provided inside the edge-dam, and the edge-dam covers the circumferential edge surface of the adhesive layer. The adhesive layer is preferably an acrylic adhesive. The protecting resin layer and the edge-dam are formed from a material of the silicone type with flame resistance. The adhesive layer is preferably provided on a substrate such as a polyimide film with flame resistance. The adhesive in the invention includes one which causes permanent adhesion.